Vacuum-tube circuits



March 24, 1 925. 1,530,620

H. s. READ vacuum TUBE cmcui'r's Filed March 1'7, 1920 Mme/Var: Har/y 6. Read Patented Mar. 24, 1925. v "ytrieezo UNITED STATES HARRY S. READ, OF NEW HAVEN, CONNECTICUT, AESIGIIGEE 'I'G WTETEBN ELMTRIC COMPANY, INCORPORATED, OF NEW YORK, N. 33"., A CQREOBATIQN 03:? NEW YORK.

VACUUM-TUBE CICIE'VGUITS.

Application filed Match 17, 3920. Serial No. 369,1?214).

l oallwhomz't may concern: scription taken in connection with the ac- Be it known that T. l-lAnur'S. READ, a citie p ny e dI'HIWElII whi h illustrates i zen of the United States, residing at New lfflventmn 33 Wh e to twwsmge Haven, in the county of New Haven, State of Connecticut, have invented certain new Refel'mng to l l 3 and 1 and useful Improvements in Vacuum-Tube Vacuum tube p fi whlch are fv Circuits, of which the following is a full, to p r cements re l 5 and Impress clear, concise, and exact descri 'tion. h P n u c e 11119 A wnven" Thi i ti l t to um b i tionul source 2 of current Waves to be to iand more ti l ly 1 h re ted 1s shownv connected to line 5. multi-stage amplifier circuits. A though frequency fmrluencleg As is well-known in the art, weakicun p f d 9 11119 m y be 0f y desired rents or i nal may b lifi d a; any :Vfili1(i,i)lll8'lll78lli3l0ll is preferably employed desired degree by impressing them on onecases Where most mp f l or more vacuum tube amplifiers arranged.- et p 2' to work into each other by suitable circuit l Tubes 3 and comm p connections. In employing a vacuum tube l Qatlwdgs 7 miles 9 and as an am lifi it h b n f d h w and grid or control electrodes 11 and 12.

tube worl zs most eiticiently when th 1 Hectmg'cnrrent for cathode 'Z is supplied pcdance between the control electrode and y battery 13, whlle mflwde 3 heated by the cathode is composed substantially of a W Gurmnt {M46118 resistance with no capacity component. In tubes 15 PPP fmm P Sources 9 that form of a vacuum tube where the conh fi f Tube 3 18 connected 1n trol electrode is within thetube and adjacent. the mcommg 11119 y t 0i & trans" the cathode, there is present a certain amount folmer Thfi Currants lmlwesgfad on the of capacity between the cathode and the en of i f p control electrode dependent in value upon P the termllmls 0f infill meqlstmfce the size and the distances between the three and consequently Change the PQ- on electrodes and the electrical constants of the cellirql electrode 1: 50 as ho Produce Correassociated circuits. -The displacement curp l 011311133 h Output Current of mt resulting from hi it efl tis tube 3. The varlatlons in the output current appreciable even for currentsvof low he of tube} are Impressed 5 ll quencies, but if the frequencies impressed of 111211 reels/tame 19 P the e L ltl'Q relatively high, suchias 50,000 or more, tllbe by causmg tube to l y Hm displacement currents are Sumcient the current Waves still further before they strength to cause a, certain amount of distorare 1ml)!essed the li (3 y 19mm tion in the current waves to be repented. of ensfol'nicr 20. In order Wei/em ill? In accordance with this invention this p y hull-which y be Present capacity client between the control electrode tween f 'fl electljode d cathode 7 i and the cathode of a vacuum tube is subf f il V Inducstantially neutralized by inserting in. series tame 21 1g i SQTW/s Wlth these 9 with the control electrdde and the cathode lgrodes w 'y one SIde of the mcflmmg an i npedance such as an'inducta nce f such llne. Thls Inductance Should b8 Of suqh e, vehic es to be resonant/with the effective value as resQnanjl Wlth the grid at it f r the frequency or bend of frecathode efiec'tive cepecity tor the frequency we quencies which are of the most importance band of frequencles that are 0 p in the impressed currents. With such an tance in the incoming Waves. With such an arrangement the inductance will neutralize arrangement this undesired capacity is neuthe capacity effect so that for the incoming tralized. and the impedance Between the grid 60 currents the impedance between the control and the cathode for the incoming currents electrode and the cathode will be substanconsists substantially entirely of resistance.

tielly all. resistance, thereby eliminating the In a similar manner, the capacity between undesired distortion in the repeated wave. grid-12 and cathode 8 may be neutralized -E'i -\This invention will be better understood by an inductance 22 of such it vuluc as to "hj reference to the following detailed debe resonant with the grid cathode" effective capacity for the important incoming frequency or hand of frequencies. i

As an example of the value inductance 22v may have, it was found that with a vacuum tube having an efiective capacity 200 mmf. between its input electrodes for a frequency of 50,000' cycles,'the inductance should be approximately five millillenrys.

It is to be understood thatthis invention may be variously modified 'from the above disclosure without departing" in any wise fronY-the spirit of this invention as defined in the appended claims.

What is claimed is: V 1. In a wave amplifying stem for amplifying a band of frequencles, an electric discharge device having an anode, a cathode and. a control electrode, the impedance betransmission'ciiiciency of said system more nearly uniform for all the-frequencies in said hand, comprising an inductance element connected directly in series with said first mentioned means, said control electrode,

and said cathode, and forming a series resonant circuit with the capacity between said control electrode and said cathode to improve the efliciency for those frequencies at which the system would otherwise have relatively low efficiency, while still permitting the efficient transmission of thoseifrequo'n- I cies of the band for which the system without said inductance has high transmission efficiency.

2. In a wave amplifying system .for amplifying a hand of frequencies, an amplifier having an anode, a cathode and 'a control electrode, a transformer having a secondary winding, a circuit including said secondary winding, said control electrode and said cathode in'series, said control electrode and said cathode having an a preciable capacity effect therebetween whic causes'sa'id amplifierto transmit certain frequencies of said and-with greater efiiciency than other he qnencies of said band, and an inductance connected directly in series in said circuit, which inductance, while remaining 1n a constant ad ustment, so resonates at a constant frequency with said capacity effect new increase the cfiiciency, at those frequencies at which the amplifier alone has relatively low efiiciency, to such a-valu'e that theWidthof the band of. frequencies which 7 the system is 'capable of vtransmitting with equal effici'ency is increased.

3. In a waveampli fying system for am- 1 plifying a band of frequencies, an amplifier having in utelectrodes between-which a ca pacity c act exists whereby said amplifier has tendency to transmit certain frequencics of said-band with greater efliciencythun other frequencies of'said band, a transformer having a secondary winding, a circuit in eluding said secondary winding'and said in' put electrodes in series, and means for rendering the transmission eiliciency of said systern more nearly uniform forall the-frequencies in said band, comprising an inductance connected directly in series in said cir- Y cuit, which inductance, whilepermitting said amplifier to transmit with substantially the same efficiency those fre ucncies-cf the band for which it has big transmission efficiency, and with the same adjustment ofv the circuit, resonates with the capacity cf; feet between said input electrodes to improve the efiiciency for those frequencies. at which the amplifier alone has relatively low ef- In witness whereof, I hereunto subscribe my name this l2th day 9f March, A. D., 1920. a

HARRY s. READ. 

